1. Field of the Invention
This invention relates generally to valved manifold devices of the type used at the patient intubation interface of neonatal endotracheal ventilation/aspiration systems. It is specifically directed to an improved valve stem interface structured to protect against accidental shearing of fragile aspiration catheters positioned within such manifolds.
2. State of the Art
Many gas delivery systems, particularly in a hospital or laboratory environment, utilize manifold devices for directing fluid flow. There is a variety of circumstances in which it is necessary or desirable to provide multiple, yet isolated, other path ways through the interior of such a manifold. The manifold is often associated with other components as a system.
As an example, closed systems for endotracheal suctioning and ventilating typically include a manifold enabling introduction of ventilating gases and intermittent exhalation of patient breath simultaneously with insertion and operation of a tracheal suctioning catheter. The manifold structure typically includes multiple ports, usually the open ends of respective conduits extending from a common chamber. One such port is interfaced to a patient through a patient connection device. The suction catheter is often included within an assembly which is connectable to a second port of the manifold. The catheter assembly conventionally includes a collapsible plastic envelope positioned entirely to surround the catheter. A practitioner manually externally collapses the envelope onto the external surface of the catheter, and advances the catheter through the manifold into an access tube connected to a patient, retracting the catheter in a similar fashion following the aspiration procedure.
The manifold thus provides a first pathway for ventilation gases, and a second pathway for the catheter. The catheter provides isolation from the ventilating gases for fluids withdrawn from the patient through the manifold. When the catheter is withdrawn, it is often desired to continue regulated ventilation through the manifold. In some cases, it is desirable for the catheter assembly to be disconnected from the manifold, without disturbing the ventilation of the patient. It is thus necessary to provide for a gas tight sealing of the pathway formerly occupied by the catheter upon its removal. Early efforts in this connection have involved the provision of auxiliary sealing structures for use in association with the manifold. Eventually, specialized valves were developed for inclusion in a manifold assembly. These valves are structured to provide a travel path for a catheter when catheter suction is needed, while maintaining an adequate seal.
Material prior art structures and methods are described, among other places, in U.S. Pat. No. 5,333,607 to Kee, et al.; U.S. Pat. No. 5,354,267 to Niermann, et al.; U.S. Pat. Nos. 5,357,946 and 5,445,141 to Kee, et al.; U.S. Pat. Nos. 5,140,983 and 5,487,381 to Jinotti; U.S. Pat. No. 5,882,348 to Winterton et al.; U.S. Pat. Nos. 5,735,271 and 5,730,123 to Lorenzen et al. and U.S. Pat. No. 5,642,726 to Owens et al. These patents each disclose ventilator manifold devices and systems in which those devices are utilized. The '267 patent, for example, discloses a manifold and a multi-position stop cock valve. The valve is provided with a “Tee” shaped internal stem channel pattern so that the stem may be positioned selectively to wash the internal lumen of a catheter, to irrigate the patient or to accommodate travel of the catheter through the stem to suction the patient. The valve may be plugged directly into an access port of the manifold. Patient ventilation is conducted without respect to the valve through other ports of the manifold. The valve itself constitutes an integral component of a catheter assembly, and must be removed from the manifold with the remainder of that assembly. The '348 patent discloses a valved manifold embodying a multi-position stop cock valve. The ventilation port is transverse the patient interface port, and is thus characterized by more dead air space than is generally regarded as acceptable for neonatal applications.
U.S. Pat. No. 6,729,326, issued May 4, 2004, to Winterton, et al., discloses an inexpensive, yet reliable, manifold assembly incorporating a valve positioned to minimize dead air space within the manifold and capable of passing a catheter. The assembly includes a valve that provides a sealed gas flow path through the manifold in both its open and closed conditions with respect to catheter travel. The assembly is particularly useful in neonatal applications, because it is constructed to minimize fluid flow turbulence of ventilating gases and to minimize the likelihood of respiratory therapy fluids introduced through an aspiration catheter from back-washing into the ventilation channel of the manifold. The valve component of the assembly is of the stop cock variety. That is, it comprises a stem or core element which is rotated between open and closed conditions within a housing. In both conditions, an open passageway, comprising a portion of the ventilation circuit, exists through the valve stem. In this arrangement, an aspiration catheter must pass through the interface between the valve stem and the inner wall of the housing to enter and pass through the interior of the stem. The disclosure of the '326 patent is incorporated by reference in its entirety as a portion of this disclosure for its teachings concerning the structure and operation of valved manifolds in medical applications.
The aspiration catheters used to aspirate adults or juveniles are sufficiently rugged to resist closure of a valve within which they are positioned. In the event that an operator inadvertently attempts to close the valve, this resistance alerts the attendant, or operator, to the presence of the catheter. Either the catheter can then be removed to permit valve closure, or it is recognized that the catheter should remain in place, and the valve should be left open. Neonatal catheters are relatively fragile, compared to those used for the aspiration of adults or juveniles. While neonatal catheters may be manufactured from similar, or the same, material as catheters for adults, the smaller size of neonatal catheters, and attendant smaller cross-section, renders such catheters more susceptible to damage. In practice, an inadvertent or mistaken effort to close the valve with such a catheter in place can result in severe damage to the catheter. It is conceivable that a distal portion of a neonatal catheter can be completely severed by action of a user closing a valve element, thereby placing an intubated patient at risk of receiving the severed tip as an undesired pulmonary implant.